I see many people growing Chlorella or Spirulina, types of microalgae, inside bottles... I see that they also insert CO2 into the bottles artificially... This question is basically comprised of two questions that will clarify this situation:
- Why do they use bottles or any type of bottle-like canister?
- Why do they insert CO2 to the bottle artificially in cases the bottle doesn't have a cork ? If the claim is that enough CO2 won't be able to get through the bottle neck than why growing the algae inside a bottle\aquarium in the first place, and not in a tub with full exposure to the air?